|Magic Affinity is a term used on magian staves that is designed to emulate the element-specific effects of the ever-popular level 51 elemental staves. These are not actually the same term in the damage equation, though they have the same effect in most cases. Affinity (Magic Damage and Magic Accuracy) was then also used as a potential Atma stat, and seems likely to retain a major role in mage playstyle in the future.
Affinity, specifically, was used to break apart the elemental staff bonuses into different portions, so that they could be adjusted independently of each other. So while Aquilo's Staff gives -3 Ice perpetuation, +15% Ice damage, and +15 Ice Magic Accuracy, an Ice Magian Staff would only give a large benefit to one of those, but with that bonus increasing as the level of the staff increases. Also, similarly to an Aquilo's Staff, it would give a penalty to the "weak" element (wind in this case) equal to bonus it gives to the appropriate element.
"Elemental Affinity: Perpetuation Cost -6" means that any avatar or spirit with the appropriate element has their upkeep reduced by 6MP/tick, to a minimum of 0 (or 1, if you count the first tick of Auto Refresh).
Staves that say things like "Elemental Affinity: Magic Damage +X" actually give an (X+1)*5% bonus to spell damage of the matching element. This is applied in a separate step from other bonuses. In the case of the opposing "weak" element, they receive a penalty equal to what the bonus would have been otherwise.
Staves with "Elemental Affinity: Magic Accuracy +X" actually give (X+1)*5 Magic Accuracy to spells of the appropriate element. They are assumed to give an equal penalty to the "weak" element.
|Affinity||Perpetuation Cost||Magic Damage||Magic Accuracy|